JUPITER, Fla. -- Full-squad workouts for the Marlins begin on Monday, but that doesn't mean two projected infield starters will be at full speed. Third baseman Martin Prado and shortstop JT Riddle are each in rehab protocol, and neither is expected to participate in Grapefruit League games until mid-March.
Prado underwent right knee surgery last season, and Riddle had left shoulder surgery. The two will spend the early part of Spring Training building back up.
"We're going to be very patient with [Prado], making sure that he's kind of stepping along," Marlins manager Don Mattingly said on Sunday. "In my mind, and I think in our minds, he's still in rehab protocol from the standpoint of we're going to keep him to a minimum and work him towards making sure he's ready [Opening Day].
"Riddle is a lot like Martin. Again, he's coming off of surgery, and I still look at him as being in rehab. He really is in kind of rehab protocol from the standpoint of he can only do this, he can only do that."
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With Prado out of game action, at least early in Spring Training, it opens opportunity for Brian Anderson, the organization's No. 8 prospect, according to MLB Pipeline. Non-roster invitees Johnny Giavotella, Eric Campbell and Peter Mooney will be among the candidates to get some time at third.
Miguel Rojas will work mostly at shortstop.
"They're talking about [Riddle] not being able to play until the middle of March," Mattingly said. "That's our earliest date. That's without anything else going on."
Prado had an injury-plagued 2017, appearing in just 37 big league games. He last saw big league action on July 17, and Riddle's last game came on July 19.
"[Prado] hasn't played in a year, if you really think about it," Mattingly said.

Last Spring Training, Prado sustained a right hamstring injury at the World Baseball Classic. He opened the season on the disabled list and reinjured his hamstring again in May.
Eventually, Prado hurt his right knee, which required surgery.
"For me, the date on Martin is Opening Day," Mattingly said. "I'd love for Martin to be ready on Opening Day."
Worth noting
• Right-hander Severino Gonzalez has been outrighted. The 40-man roster is now at 39.
• Miami's first Grapefruit League game is on Friday, when the Marlins are the home team against the Cardinals at 1 p.m. ET at Roger Dean Chevrolet Stadium. Dillon Peters, the Marlins' 11th-ranked prospect, according to MLB Pipeline, will make the start. He is tentatively set to throw two innings.
• Since there are just four days before the first game, the hitters will waste little time seeing live pitching. On Monday, the first day of full-squad workouts, pitchers will face hitters.
• The Marlins will have 12 of their top 30 prospects, per MLB Pipeline, on the field on Monday. The list includes their top three prospects -- Lewis Brinson, Monte Harrison and Sandy Alcantara, respectively. Rounding out the top 30 list are: Magneuris Sierra (7th), Anderson (8th), Isan Diaz (9th), Nick Neidert (10th), Peters (11th), Merandy Gonzalez (13th), Zac Gallen (18th), Trevor Richards (27th) and Pablo Lopez (30th).
Up next: Full-squad workouts get underway at 1 p.m. ET on Monday on the back fields at the Roger Dean Chevrolet Stadium complex in Jupiter. Miami has 68 players in camp. Workouts are open to the public.